Coca-Cola is the sponsor through 2020, I assume they're renewing but...
The Tour Championship used to be in Sept or Oct , right? And it “moved around” to places like Champions, Olympic, Oak Hills (San Antonio), even Pebble and Pinehurst. With a new August date, in addition to West Coast venues like Chambers Bay, Pumpkin Ridge, etc., maybe those courses in the Northern latitudes would be a good fit as May might prove a challenge weather-wise to host the PGA Championship. Hazeltine… Oak Hill… Inverness… Whistling Straits. Maybe even Colorado GC, Phila. Cricket, and/or Baltimore CC.
Just spit-balling as they say…